If I were dictator and could order specifications for The Next Universal Lossless Audio Codec, I can think of a quite a few improvements, but let me rather offer my $2e–02 on the 'why FLAC is standardizing' (which I am not sure will be true for forever, given the power of The New Microsoft with the fruity logo and name).

First: there need not be any 'good' reason why one product dominates over another market-wise. And especially not here, where compatibility is more or less everything as soon as features are 'good enough'. If N equally good codecs share the market evenly, that is most likely an unstable equilibrium. Whichever gets the upper hand (even if just by coincidence) will have better chances of growing quicker. And when concerns 'good enough' ... that TTA can sample at 4 GHz is certainly nothing compared to compatibility.

I would suppose that the main reason for FLAC's success, is being at the right place doing the right thing at the right time. And I can only guess that parts of this 'right thing', were- optimized for decoding speed. Ten years ago, I think that was fairly important (and maybe even today for portable devices): it didn't require much CPU load. (AFAIK, no codec improved over FLAC on both compression and speed simultaneously until TAK, am I right?)- licensing. Free, could be used in any device.- quite future-proof feature-wise, at least for quite a few years' horizon. (Compare to Shorten and WAV ... and their tagging ...)- good enough compression ratio. I mean, most don't even use the –8 switch.And the right place, would be under the wings of Xiph, who had gained a reputation after doing Vorbis at the time when manufacturers were worried about licensing costs for MP3.

Compare to the competition at (approximately) that time: WavPack (1998) and Monkey's (2000?) decoded slower, and not to mention the closed-sourcers LA (2002) and OptimFrog (2003). LPAC was also closed source, and not to mention WMA Lossless, which was release at a time where Microsoft was getting knocked big time for their attempts at locking-in, and at the same time everything DRM-enabled was getting the middle finger big time. Meridian Lossless has some market though, on physical media, but has never target the 'decode yourself' market.

I have to say though, that I don't really understand why WavPack didn't catch on, being so early available. Though I don't know what features it had back in last century.